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At least 649 records · Page 36Linked to original sources
PubMed1990

Responses of single phrenic motoneurons to altered ventilatory drives in anesthetized dogs.

We studied the effects of altered ventilatory drives on the activity of the whole phrenic nerve and single phrenic motoneurons in dogs anesthetized with alpha-chloralose and paralyzed with gallamine triethiodide. Single phrenic motoneurons were classified as either late-onset or early-onset motoneurons (LOM and EOM, respectively), depending on the time of onset of their activity during inspiration. Increase in ventilatory drive was induced by altering chemical drive with changes in arterial blood gases and also by altering the vagal afferent contribution to ventilatory drive. The latter was accomplished by inducing pulmonary gas embolism (PGE) during hyperoxia. Whole phrenic nerve activity was increased by both types of increase in ventilatory drive. In both cases, changes in the firing pattern of LOMs and EOMs were responsible for the increased phrenic output. The changes in post-PGE firing pattern of the LOMs generally consisted of a shift in the time of onset to an earlier point in inspiration and an increase in the number of spikes per inspiratory cycle. Vagotomy abolished the difference between the contributions of LOMs and EOMs to the phrenic response to PGE. Data from dogs studied while they were breathing spontaneously were qualitatively the same as those from the paralyzed animals, indicating no major role for phasic volume feedback in these responses. Our data regarding altered chemical drive are similar to those reported earlier in other species, whereas those regarding PGE demonstrate that vagally mediated increases in ventilatory drive affect both LOMs and EOMs, although LOMs are affected to a greater degree.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1994

Depression of hypercapnic ventilatory drive by testosterone in the sleeping infant primate.

In postnatal infants, there is similarity between the time course of transient gonadal steroid secretion and the age-related incidence of sudden infant death syndrome (SIDS). The cause of death in SIDS is generally thought to be a ventilatory arrest, but the mechanism responsible for such an event remains unknown. Testosterone has been demonstrated to depress ventilatory drive and increase sleep apnea in adult men. We tested the hypothesis that the gonadal steroid testosterone depresses infant ventilatory drive during sleep. Three newborn male infant primates were gonadectomized after birth. Ventilation was observed and quantified for each animal during completely natural unencumbered sleep by plethysmography for an average of 16 wk. Ventilatory patterns were recorded, and ventilatory drive was challenged with hypercapnia and hypoxia during quiet sleep on the night before and the night after testosterone administration. Hypercapnic ventilatory drive during sleep was significantly depressed by an average of 33.6% on the night after compared with the night before testosterone administration. Depression of the response to hypercapnia after testosterone was not accompanied by any change in resting minute ventilation measured during quiet sleep. Hypoxic ventilatory drive, incidence of apneic events, and length of apnea were not different after testosterone. The effects of injecting a placebo on ventilatory patterns and drive were tested by giving the placebo to all animals on several test weeks. Placebo injections produced no significant change in any measured parameters. These results support the hypothesis that testosterone depresses hypercapnic ventilatory drive during sleep in the infant primate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Use of twitch pressures to assess diaphragmatic function and central drive.

Transdiaphragmatic pressures generated by phrenic nerve twitches have been proposed as a means to assess diaphragmatic function and central drive, but their validity and reliability have not been determined. We evaluated diaphragmatic twitch and twitch occlusion measurements in a rabbit model of diaphragmatic contractile dysfunction and diaphragmatic fatigue to determine whether 1) diaphragmatic twitch pressures accurately assess changes in low- and high-frequency diaphragm trains during the development of, and recovery from, contractile fatigue; 2) twitch occlusion measurements accurately quantify the intensity of central drive to the diaphragm; and 3) twitch measurements are affected by thoracoabdominal binding or twitch potentiation. Single-twitch and 20-Hz double- and triple-twitch pressures accurately reflected changes in low-frequency diaphragm train pressures, whereas only 80-Hz triple-twitch pressures accurately reflected changes in high-frequency trains. Twitch occlusion measurements of central drive closely mirrored central drive as reflected by phrenic nerve recordings and only slightly underestimated the absolute intensity of central drive. Thoracoabdominal binding increased twitch and train pressures, and repetitive electrical stimulations further potentiated twitch pressure. However, twitch potentiation and a lack of thoracoabdominal binding had no effect on twitch measurements of diaphragmatic function during the induction and recovery from fatigue or on twitch occlusion measurements of intensity of central drive. Thus, twitch measurements can be used to accurately assess diaphragmatic low- and high-frequency fatigue and to quantify the intensity of central drive to the diaphragm.

Anesthesia↗
PubMed1993

Lisinopril lowers cardiac adrenergic drive and increases beta-receptor density in the failing human heart.

BACKGROUND: In subjects with heart failure, angiotensin converting enzyme inhibitors exhibit mild systemic antiadrenergic effects, as deduced from treatment-related lowering of systemic venous norepinephrine levels. The effects of angiotensin converting enzyme inhibitors on cardiac adrenergic drive in subjects with heart failure has not previously been investigated. METHODS AND RESULTS: In a placebo-controlled, double-blind crossover study of 14 patients, we measured cardiac and systemic adrenergic drive, myocardial and lymphocyte beta-adrenergic receptors, and hemodynamic changes at baseline and after 12 weeks of therapy. Relative to placebo, lisinopril therapy was associated with only minimal, statistically insignificant changes in hemodynamics, a significant increase in myocardial beta-receptor density, no significant (P < .05) changes in cardiac or systemic adrenergic drive, and no detectable change in lymphocyte beta-receptor density. When subjects were rank ordered into groups with the highest and lowest coronary sinus norepinephrine levels, those with the highest norepinephrine levels exhibited significant decreases in central venous norepinephrine, coronary sinus norepinephrine, and an increase in myocardial beta-receptor density relative to changes in placebo or relative to baseline values. Subjects with lower cardiac adrenergic drive exhibited no significant changes in coronary sinus or systemic norepinephrine levels or in myocardial beta-receptor density. CONCLUSIONS: The angiotensin converting enzyme inhibitor lisinopril lowered cardiac adrenergic drive and increased beta-receptor density in subjects with increased cardiac adrenergic drive but had no effects on these parameters in subjects with normal cardiac adrenergic drive. These data suggest that cardiac antiadrenergic properties contribute to the efficacy of angiotensin converting enzyme inhibitor in subjects with heart failure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1983

Interactions among behavioral style, ventilatory drive, and load recognition.

We previously demonstrated that specific behavioral styles influenced recognition of resistive loads to breathing. However, the basis for this finding remained unclear. Because others have found a relationship between behavioral style and ventilatory drive, we evaluated the relationships among resting ventilatory drive, behavioral style, and recognition of loads to breathing. Twelve healthy subjects were divided into 3 behavioral style groups by the MMPI Panic-Fear Scale. Inspiratory neuromuscular activity, detected by mouth occlusion in relaxed subjects, served as an index of resting ventilatory drive, and the resistance added to inspiration recognized during 50% of the applications was termed threshold resistance. Across all subjects, there was a significant inverse correlation between resting inspiratory neuromuscular activity and the amount of added resistance required for recognition. The higher the ventilatory drive the lower the added resistance needed for recognition. Anxious, dependent subjects had lower resting ventilatory drive and lower mean inspiratory flow rates. They required more added resistance for recognition than generally adaptive or rigidly independent subjects who had higher resting neuromuscular activity and lower detection thresholds. We conclude: (1) that the level of resting ventilatory drive may play a role in the ability to recognize added resistive loads to breathing, and (2) that behavioral style and level of resting ventilatory drive appear related.

Adult↗
PubMed1989

Quantitation of photic driving in dementia with normal EEG.

The EEG is frequently normal when early dementia is clinically suspected. The presence or absence of occipital driving with intermittent photic stimulation is not helpful in detecting cerebral pathology, but quantitation of photic driving was shown to distinguish between dementia and depression in geriatric patients. We quantified photic driving in twenty clinically demented patients without diffuse or focal EEG abnormality, and compared this in 20 age-matched normal controls. Intermittent stimulation at odd-numbered frequencies between 1 and 31 Hz was carried out. The product of frequency of stimulation and duration of driving response was determined, and the incidence of absent, subharmonic and supraharmonic photic driving was determined. The quantitative measure of frequency times following duration was significantly greater in the nondemented individuals than in demented patients with normal EEGs. More nondemented individuals demonstrated supraharmonic and subharmonic responses than did demented patients. The range of normal variability in persistence, duration, and symmetry of photic driving is great, and caution in determining abnormality on this basis is appropriate. Subtle but measurable changes in photic driving may occur early in dementing illnesses, however.

Aged↗
PubMed1997

Nervous control of male sexual drive in the hermaphroditic snail

We studied the role of the prostate gland in determining the level of male sexual drive in the hermaphroditic pond snail Lymnaea stagnalis. Male sexual drive is high after a period of social isolation and decreases after copulation as a male. A positive correlation exists between the level of male sexual drive and the volume of the prostate gland. Like male sexual drive, the volume of the prostate gland increases during a period of social isolation and decreases after copulation as a male. Behavioural experiments demonstrated that animals with a lesion of the nerve that innervates the prostate gland (NP1) have a lower level of male sexual drive after social isolation than control animals. However, lesion of NP1 did not affect the increase in the volume of the prostate gland caused by social isolation. Extracellular recordings from NP1 in a semi-intact preparation show a change in firing pattern during an experimentally induced increase in prostate gland volume. The results indicate that NP1 serves as a nervous pathway for the male sexual drive. We propose a simple motivational model for male sexual behaviour in L. stagnalis in which the volume of the prostate gland sets the level of male sexual drive.

Journal Article↗
PubMed2002

Effect of news coverage on the prevalence of drunk-driving behavior: evidence from a longitudinal study.

OBJECTIVE: To examine the proposition that antidrunk driving messages in the news media contributed indirectly to the decline in drunk driving over the past two decades through their impact on related policy making processes. METHOD: Time series regression techniques are applied to longitudinal data to examine the causal association between drivers' involvement in drunk-driving behavior, the volume of news coverage devoted to the drunk driving issue, and related policy making. RESULTS: Results show a significant contribution of news coverage to drunk-driving-related policy actions, which in turn are associated with a reduction in drunk driving among young and high-risk drivers. There was no evidence of a direct causal association between news coverage and change in drunk-driving behavior. CONCLUSIONS: News coverage of alcohol-related risky behaviors seems to provide a cost-effective way of reducing the prevalence of these practices by attracting institutional attention and prompting related environmental changes. Future interventions may benefit from actively seeking to influence news coverage of risky behaviors.

Accidents, Traffic↗
PubMed1994

Ergonomic aspects on snowmobile driving.

From self-reported health surveys in Finland, Sweden and Norway we know that the reindeer herders have work related disorders. It is very likely that disorders such as lumbar back pain, neck and arm pain, knee pain and white finger syndrome are related to snowmobile driving. Our hypothesis was that driving postures, vibrations, impact from the driving surface and handling are the main reasons for the health problems, and that snowmobiles are not designed according to ergonomic principles. Our work started in the winter of 1993. We studied the general literature available on ergonomic postures, measurements of vibrations and body impact and we set out to explain the problems associated with driving and handling snowmobiles from a physiological, ergonomic and biomechanical point of view. At this point we identified some ergonomic requirements and requirements for the springing system of snowmobiles. We made static tests in which we watched the sitting position of the driver and tested the springing suspension. This was followed by a driving test and field observations of reindeer herders in 1994. The total load when driving comprises the load of the posture added with the load from vibrations and impact from the ground (3-10 G). The driving positions probably giving the most health problems are sitting with bent back, hyperlordotic neck, too high upper arms, more or less straight elbows and flexed and ulnar deviated wrist positions. The design of the snowmobile should enable the driver to sit with straight back, the hip joints at less than 90 degrees, knee joints at about 45 degrees, shoulder joints at 45 degrees, elbow joints around 60-70 degrees and the hand in a neutral position. The seat should be higher at the back and narrowed between knees. The height of the seat should be about 50 cm. The height of the steering-bar should be around 80 cm. The distance between the body of the driver and the steering-bar should be about 50 cm. Only one snowmobile was close to our requirements with a seat height of 48 cm and steering-bar height of 75 cm. The seat height varied with 10 cm, and the height of the steering-bar from 64 to 75 cm. The gas-bar should be placed on the thumbside so that it is possible to use the accelerator with the fingers.(ABSTRACT TRUNCATED AT 400 WORDS)

Ergonomics↗
PubMed1998

Age-related differences in risks of drinking and driving in gender and ethnic groups.

We examine the extent to which empirically observed age-related differences in rates of drinking and driving can be explained by concurrent differences in drinking patterns. Building on previous research showing significant age differences in drinking patterns between men and women and among three ethnic groups, Whites, Blacks, and Hispanics, our study considers whether there are unique gender and ethnic group differences in patterns of drinking and driving. Data were from 4395 respondents 12 to 80 years old in a general population survey of 20 urban areas in the United States. During the month preceding the interview, 1130 (25.7%) of all respondents had driven after having one or more drinks. Drinking pattern measures included drinking frequency, average drinking quantity, and the variance in the number of drinks consumed per occasion. To assess the relationships of drinking patterns to drinking and driving across age groups, two sets of analyses were conducted, one set in which age differences in drinking patterns were statistically controlled and one set in which they were not. Although the statistical control for drinking patterns reduced age differences between gender and ethnic groups, it did not eliminate them. The reduction demonstrated that part of observed group differences in driving after drinking over age among gender and ethnic groups is due to age-related differences in drinking patterns. However, despite controlling drinking patterns young respondents remained more likely to drink and drive. A supplementary analysis of self-reported incidents of driving while intoxicated (i.e., driving after having five or more drinks) further indicated that, controlling for drinking patterns, young respondents are most at risk.

Accidents, Traffic↗
PubMed2002

Aggressive driving: a preliminary analysis of a serious threat to motorists in a large metropolitan area.

OBJECTIVE: Aggressive driving is consistently rated as the leading concern of motorists in our metropolitan area, ahead of even "drunken driving." Few objective data exist on the incidence of aggressive driving. The purpose of this study was to determine the incidence of selected aggressive driving behaviors and to establish a baseline for future interventions and research. METHODS: Speeding, traffic signal violations ("red-light running"), and stop-sign violations were studied. Speeding data were recorded by inductance loops embedded in major roadways (n = 10). Data were collected from red-light cameras (n = 73 cameras, 82 sites) and by trained observers at intersections with traffic signals (n = 15) or stop signs (n = 15). Data included total traffic volume, numbers of violations, and each violator's speed. RESULTS: The majority of motorists on major roadways drive at speeds exceeding the speed limit and between 40% and 80% of vehicles were traveling at 10 mph or more over the speed limit. Red-light running occurred at equivalent rates both by camera (1.5 violations/1,000 vehicles) and by observer (1.3 violations/1,000 vehicles). The absolute numbers of red-light violations were extremely high (approximately 30,000 per month), and 16% violated the signal at > 10 mph above the speed limit. The incidence of "at-speed" (i.e., without slowing) stop-sign violations was dramatic (17.5 violations/1,000 vehicles). These were confirmed by video review and represent high risk for crashes. CONCLUSION: Aggressive driving behaviors are frequent and often include very dangerous actions. Currently available deterrents appear to have limited impact in our congested area. Inadequate resources for enforcement and limited public awareness may be partially responsible. We have adopted a multidisciplinary approach to this serious problem including public education, stepped-up enforcement, and psychological treatments.

Accidents, Traffic↗
PubMed2005

Effects of fexofenadine and hydroxyzine on brake reaction time during car-driving with cellular phone use.

Antihistamines are a mainstay treatment for allergic rhinitis; however, many older agents cause adverse events, including sedation and central nervous system (CNS) impairment. Research has shown sedating effects of antihistamines on driving; currently, no known study has examined whether cellular phone usage while driving further compounds impairment in individuals administered antihistamines. The aim of this study was to examine this endpoint. In a randomized, double-blind, placebo-controlled, three-way crossover study, healthy volunteers received fexofenadine HCl 120 mg, hydroxyzine HCl 30 mg and placebo. Brake reaction time (BRT) was used to examine driving performance across four conditions: driving only; driving while completing simple calculations; complex calculations; and conversing on a cellular phone. Subjective sedation assessments were also conducted. Brake reaction time with and without cellular phone usage in fexofenadine-treated subjects did not differ significantly from placebo in any condition. In contrast, hydroxyzine-treated subjects were significantly more sedated and had slower BRTs, suggesting slower hazard recognition and brake application, compared with the fexofenadine and placebo groups in all conditions. Importantly, cellular phone operation was an additive factor, increasing BRTs in hydroxyzine-treated volunteers. Fexofenadine did not impair CNS function in subjects involved in a divided attention task of driving and cellular phone operation.

Adult↗
PubMedDate not supplied

Medication and fitness to drive.

PURPOSE: The aim of this study is to analyze the consumption patterns of medicaments among motor vehicle drivers who attend 'Medical Driving Test Centres' and the relation between habitual consumption of medicaments and fitness to drive. METHODS: The study was carried out on 8043 drivers who attended 25 Medical Driving Test Centres. RESULTS: 24.7% of drivers chronically consume medicaments while 6.8% consume medicaments along with alcohol every day. Of those who chronically consume medicaments with a warning about the medications on driving, 65.8% were considered 'fit' to drive, 27.3% 'fit with restrictions', 5.1% 'suspended' and 0.4% 'unfit'. CONCLUSIONS: The results show how frequent the consumption of medicaments along with alcohol is and that the great majority of drivers who take medicaments are considered fit to drive.

Adolescent↗
PubMed1981

Latent portasystemic encephalopathy. I. Nature of cerebral functional defects and their effect on fitness to drive.

Forty patients with chronic liver disease and portal hypertension but without clinical signs of portasystemic encephalopathy (15 patients with nonalcoholic cirrhosis, 15 patients with alcoholic cirrhosis, and 10 patients with minimal EEG changes) and a control group of 12 patients with chronic alcohol pancreatitis were studied using an extensive psychometric program, which, in the same form, is used for expert reports on driving capacity. Of the cirrhotic patients, 60% were considered unfit to drive; in 25% driving capacity was questionable, 15% (only nonalcoholic cirrhotics) were considered fit to drive. In contrast 75% of the patients with alcoholic pancreatitis were considered fit to drive. Major defects were found only in three heavy alcoholics. Patients with alcoholic cirrhosis scored lower than patients with nonalcoholic cirrhosis. This was due to differences in liver function rather than to the effect of alcohol consumption. Patients with minimal EEG changes were practically all considered unfit to drive.

Adult↗
PubMed1992

Methods for testing impairment of driving due to drugs.

The Transport and Road Research Laboratory has been concerned for a long time with possible causes of driving difficulties and has developed methods for investigating driving performance. The question addressed here was how applicable these methods are in assessing driving problems arising from the use of drugs which can impair performance, particularly widely-available centrally-acting drugs. We assessed four types of driving-related tests by comparing their sensitivities with two laboratory tests, developed elsewhere, which measure more basic effects of drugs on performance, using drugs known to impair skills. Performances under the influences of ethanol, the benzodiazepine lorazepam, and the antihistamine triprolidine, each given both as a single high dose and a single low dose, were compared with performances after placebo. We used double-blind crossover design, in which subject variability was minimized by studying only women of a limited age range (45-55 y). The driving-related tests detected the effects of the substances used, although they were generally less sensitive than the laboratory tests. The individual sensitivities of the driving test could be improved to match those used for more general assessments.

Automobile Driving↗
PubMed1999

[Expert-assessment of suitability for a driving license in otorhinolaryngology].

An absolute requirement for acquiring a driving license according to German law consists in the suitability for driving a motor vehicle. The "driving license decree" defines these requirements; in case of doubt the administrative authority may demand a medical certificate. According to law (enactment: 1.1.99) these medical certificates must be refunded by either appropriate medical specialists, company doctors or public health officers. The criterions for appraisal are set down in the guidelines for driving ability which are edited by the advisory board for traffic medicine; a new edition will be published soon. Concerning otorhinolaryngology hearing impairment and dizziness are the most relevant diseases. Bilateral deafness is no general exception for conferring a driving license for the classes A and B; for classes C and DE hearing loss, established from the pure tone audiogram must not exceed 60%; an exceptional case is a three year demonstration of reliability in class B. Permanent dizziness or vertigo attacks are in most cases incompatible with conferring driving licenses. The most important issue for medical appraisal is to determine the amount of compensation of the impaired sense organ. Therefore in cases of multiple disabilities more stringent criterions must be established.

Automobile Driving↗
PubMed1998

[Night driving capacity of ophthalmologically healthy persons of various ages].

UNLABELLED: In 1970 Aulhorn and Harms made fundamental recommendations for the night driving ability of motorists as well as for the corresponding examination methods. Reduced night driving ability of persons over the age of 60, as well the established limits for twilight vision and glare sensitivity, and their relevance to night-time collisions has been re-examined. PATIENTS AND METHODS: A total of 117 normal volunteers between 10 and 79 years of age underwent ophthalmological examinations including measurement of contrast acuity and glare sensitivity by means of the Mesotest II (Oculus, Germany). RESULTS: Contrast acuity and glare sensitivity deteriorate in an age-dependent fashion. Thus, night driving ability decreased with increasing age. The majority part of persons over the age of 60 were not able to fulfill the actual criteria for night driving ability according to the recommendations of the German Ophthalmological Society (DOG). CONCLUSIONS: In the present population, nearly 40% of persons over the age of 60 have reduced night driving ability. Since Lachenmayr showed in the BAST study the correlation of reduced night driving ability and car accidents, this emphasizes the importance of ophthalmological check-ups for motorists at this age.

Adolescent↗
PubMed2000

[Perimetry findings and driving performance. "How much visual field" does a motorist need?].

OBJECTIVE: On 01-01-99 the new driving licence regulations came into force. Are the visual field criteria mentioned there sufficient for an adequate evaluation of driving fitness? METHODS: Typical (binocular) visual field defects were digitally superimposed onto photographs of traffic scenes to show the influence of such scotomata on visual perception. RESULTS: Exemplary cases clearly show that evaluation of visual field borders alone is not sufficient for evaluating driving fitness. They also prove that binocular scotomata affecting the (para-)central region of the visual field are of special importance to driving performance. The actual guidelines given by the traffic commission of the German Ophthalmological Society (DOG) and the legally defined limits will be critically discussed. CONCLUSION: From the ophthalmological point of view the actual visual field criteria of the new driving licence regulations do not seem to be sufficient for the evaluation of driving fitness: An additional consideration of (para-)central scotoma is mandatory. This publication provides recommendations for execution and interpretation of perimetric examinations for traffic ophthalmological purposes.

Automobile Driver Examination↗